All edges angles initialized to zero

[jgao222]

The angle that each edge has is intended to be the angle between the normals of the faces that contain that edge.
Currently they are all initialized to zero, so folding from anything that isn't initially a flat sheet won't work correctly.

[jgao222]

FOLD library has a method to generate normals from a triangle, and get the angle between things, so that should be a place to start.